The present invention is directed generally to an electrically addressable matrix display, and more specifically to a matrix display film incorporating electrically activatable, reflective particles and a method of manufacturing the film.
Some flat displays are based on the movement of electrically activatable particles under the influence of an applied electric field. In one approach to fabricating such a display, bichromal, electrically responsive particles twist under the application of an electric field to orient one or other color of the particle""s surface in a viewing direction. The particular color that is oriented towards the viewing direction is dependent on the polarity of the applied electric field. Typically, the bichromal particles are spherical in shape and are suspended in a dielectric liquid.
A second approach includes the use of particles that translate within a surrounding fluid under the influence of an applied electric field. Typically, the particles and the fluid have contrasting colors, e.g., the fluid is a dark-colored dye and the particle is colored white. When a specific polarization of electric field is applied to the device, the particles move towards a viewing surface, displacing the chromatically contrasting fluid to become visible to the viewer.
The full potential of these approaches to fabricating a flat display has not yet been realized. The existing devices suffer from low contrast and low resolution. In addition, the devices produced to date are thick, thus requiring large operating voltages to produce a sufficiently large electric field across the electrically activatable particles for activation.
There is, therefore, a need to improve the contrast, resolution, and operating voltage of such devices.
Generally, the present invention relates to a display film and a method of making same. The invention is generally directed to a method of making a display film having one or more monolayers of electrically active particles. The invention is also directed to a display having particles selected from a production distribution of particles.
In one particular embodiment, the invention is a display film, having a polymer layer with first and second surfaces. First and second monolayers of reflective particles are disposed within the polymer layer, the reflective particles being movably responsive to an electric field applied through the polymer layer. The reflective particles in the first monolayer have a first distribution of diameters over a first diameter range, and the reflective particles in the second monolayer have a second distribution of diameters over a second diameter range different from the first diameter range. The first and second distributions of diameters form portions of a production diameter distribution.
In another embodiment of the invention, a method of making a display film includes applying a monolayer of reflective particles over a first polymer coating, covering the reflective particles with a second polymer film having an upper surface; and applying the upper surface of a first portion of the second polymer coating to the upper surface of a second portion of the second polymer coating.
In another embodiment of the invention, a method of making a display film includes applying a first monolayer of reflective particles over a first polymer coating, covering the first monolayer of reflective particles with a second polymer coating, applying a second monolayer of reflective particles over the second polymer coating, and overcoating the second monolayer of reflective particles with a third polymer coating.
In another embodiment of the invention, a method of making a display film includes pressing, towards each other, first and second liner sheets, having a first layer of polymer mixed with electrically responsive reflective particles therebetween, so that the first layer of polymer mixed with reflective particles has a first selected thickness.
Yet another embodiment of a method of forming a display film includes applying a first polymer layer containing a first monolayer of first bichromal, electrically responsive, reflective particles onto a first surface of a second polymer layer containing a second monolayer of second bichromal, electrically responsive, reflective particles.
The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures and the detailed description which follow more particularly exemplify these embodiments.